The television industry has evolved and continues to develop a wide variety of components functioning to receive and display, or record, television signals. Videotape or cassette recorders (VTR, VCR) have become common companions to television receivers. The VCR is sold with a continually expanding variety of advanced features permitting the VCR conversant user to achieve a variety of convenient results. For example, the user may program the VCR for the unattended recordation of various selectable channels at various times. Video recorders universally incorporate a signal splitting function such that all signals from a given source advantageously can be supplied to a companion television receiver as well as the VCR. This permits the recording of any selected source channel while at the same time conveying all source channels to the companion television receiver for immediate viewing of the same channel or of any other. Television receivers similarly have been provided with convenient embellishments such as "picture in picture", on screen channel identification, and the like.
Of substantial convenience to the user, hand-held remote controls for both VCRs and TV receivers have been developed and are essentially universally used for their control. By simply momentarily depressing a button actuated channel number or function switch on the remote controller, a coded infrared (IR) signal is broadcast to a photosensitive receiving circuit at the recording or receiving device to carry out the mandated control input.
The broadcasting performance of television programs also has undergone and continues to undergo change. Classically, the channel designated NTSC video signal has been broadcast for antenna reception at TV receivers. Cable systems, initially intended to bring television broadcasts to remote areas of the country, then expanded to the urban environment with the development of satellite "superstations" and "premium" channels for the use of which subscribers are billed. To provide a complete service by cable, the cable TV operators typically supply a "bundled" package of local channels and superstations as standard, or non-premium channels; while the premium channels are sold individually for an extra charge. A cable subscriber will typically receive all the standard channels and perhaps one premium channel such as HBO, TMC, MAX, or the like. Pay per view services are also offered. To protect the premium and pay per view presentations, cable companies typically will "scramble" the transmission of those broadcasts and, in turn, install a "descrambler" with each subscriber, which may then in one way or another be activated by the cable operator to permit viewing by a subscriber who has purchased the premium signal. Interestingly, the typical descrambler is only capable of operating on one particular frequency, necessitating that any premium channel selected for viewing or recording must first be converted to that one frequency before it can be descrambled. Thus, the descrambler must be connected to the output of a frequency "converter box" or integrated into one. All channel tuning functions then, for both standard and premium channels, must by necessity be accomplished within the converter box. The converter, in effect, functions as a television receiver having an output which is directed to one channel, for example channel 03of the subscriber's receiver. It becomes the channel tuning facility for the subscriber, for which he must normally pay a monthly rental fee. A remote control for the converter is typically offered to the subscriber, for yet another monthly fee.
The use of the described converters/descramblers causes many problems. Often, the descrambler is of such a design that it is activated continuously, even during the use of non-scrambled channels. This causes serious degradation of picture quality. Thus, even though the subscriber may have a high quality television system, that system is limited by the quality and type of the "cable box". Of particular interest, once the channel selection is required to be carried out by the converter box, the subscriber's TV and VCR controls can no longer be used for channel selection, nor can the remotes of those devices. Thus, for any television signal source representing the output of the converter box, the advanced features of the VCR cannot be employed. For example, the device cannot be programmed to record a selected channel at a future time and, for example, a different channel at another time, inasmuch as the channel tuning capability of the VCR has been lost. In similar fashion, the enhancement of the television receiver itself, for example displaying channel names or numbers or providing for picture in picture operations are lost. Even worse, it is no longer possible to record one channel while watching another, as the converter box is the only functioning tuning device. To ameliorate this, some cable operators will rent the subscriber two converter boxes, a less than desirable solution. It is clear that many desirable aspects of the subscriber's purchased equipment necessarily have been lost. The dilemmas posed to subscribers as above described in the United States has reached governmental consideration, for example, in the Cable Television Consumer Protection and Competition Act of 1992.
In an attempt to remedy these problems, many subscribers have resorted to the use of a splitter in conjunction with a simple RF, AB switch to select between standard channels received by cable or the output of the converter box. Here, the splitter is connected between the incoming cable and the converter box input. The split-off cable signal (Source A), or the output of the cable converter box (Source B) may then be mechanically switched into the "cable-ready" input of the subscriber's receiver. At times when the descrambler is not required, the cable operator's equipment is "bypassed" by selecting Source A, thus restoring all features and capabilities of the TV and VCR. However, many subscribers find this switching arrangement difficult to install, and the lack of remote-control switching is very inconvenient given that all other functions of the subscriber's equipment are generally remote-control. Although AB switches have become available which are actuated from a dedicated remote-control unit, it is generally considered that subscribers would loathe to acquire still another control device dedicated to this function. Further, if it is desired to employ this switching function independently for both the TV and VCR, this bypass procedure becomes much more complicated. While relatively complex "integrated" switching systems are available for this purpose through retail electronic outlets, they suffer from the same drawbacks as described for the AB switch. What's more, they typically incorporate additional signal splitting functions to achieve the logic of providing independent selection of either source for presentation to a VCR or TV receiver. With each such splitting procedure, of course, a degradation of signal strength is induced which represents approximately a 35% signal loss. While some of these devices will incorporate an amplification function to compensate for this, this may introduce other forms of degradation, and necessarily increases the cost of the device.
The difficulties encountered by televisions' component users having different signal input sources also occur outside of the field of cable, for instance, in satellite reception, antenna-based reception in combination with others, and the like. Accordingly, a userfriendly source control technique which returns many of the advantageous features of the receiving units including remote actuation, should be well received by the television viewing public.